AE 2020 rotoscope not working

Hello everyone.

   I have AE 2020, and I've been using the roto brush for awhile now with no problem, but now have an issue. I rotoscoped around an object and when I go to propagate it, the rotoscope disappears right after frame 1. It completely disappears, and I can't do the shot for my movie. Does anyone know how to fix this issue? Thanks